I am pretty sure the pan has a metric thread. Most newer engines do. You can find an oil drain kit with a metric thread at www.inboardonline.com just search for part number 511009. The cost is $24.58. I know this kit fits Indmar oil pans after 1993 I believe so it should fit on a MerCruiser.

Dave, I tried this. It didn't work. There is barely enough clearance between the hull and pan/plug. It is a nightmare install. Also the hose on those kits is too short to get out the bilge drain. You would need to lengthen the hose. If you did it might work. After a few hours and scaring myself by twisting the brass fitting too hard to get it to point rearward (I thought I stripped the plug threads at first), I quit and bought a Pela oil extractor which works great.